A High‐Current‐Tolerant Multimetallic Phosphide Electrode for Alkaline Water Electrolysis Toward Industrial Conditions

ABSTRACT The development of electrocatalysts that maintain high efficiency and durability at industrial current densities remains a pivotal challenge for alkaline water electrolysis. Here, we present a high‐performance phosphide‐modified multimetallic hydrogen evolution reaction (HER) catalyst, NiFe 0.33 RuO x @P, with high‐current‐tolerant and low noble‐metal content. In this catalyst, Ni and Fe mainly exist as phosphide‐derived species with partial surface oxidation, while Ru is predominantly present as RuP‐like active domains embedded in the multimetallic matrix. The electrolyzer with a Ni foam anode and NiFe 0.33 RuO x @P cathode delivers an exceptional current density of 1.7 A cm −2 at 2.0 V under 6 M KOH (≈ 30%) at 70°C, demonstrating outstanding industrial‐level performance. This catalyst requires an overpotential of only 72 mV to achieve 100 mA cm −2 for HER in 1 M KOH, lower than commercial Pt/C. Critically, it sustains stable operation for over 200 h in 6.0 M KOH at 500 mA cm −2 . Scalability is confirmed on a 25 cm 2 electrode, underscoring its practical potential. The exceptional stability and activity are rooted in a phosphorus‐tuned electronic structure that yields a near‐optimal hydrogen adsorption free energy (ΔG H* tuned from +0.498 to −0.153 eV).